1. Field of the Invention
This invention relates to the curing of polymeric compositions. This invention further relates to the curing of hydroxy-terminated aliphatic prepolymers having pendant alkyl azide groups with isocyanate-terminated aliphatic prepolymers having pendant alkyl azide groups.
2. Description of Related Art
In the manufacture of solid rocket propellants, a polymeric substance is frequently employed as a binder to hold together fuel and oxidizer compounds of the propellant. The binder may, of course, supply fuel or oxidizer elements itself. Certain of the polymeric binders are prepared from hydroxy-terminated prepolymers. The addition of curing agents to these prepolymers causes cross-linking between the functional groups of the prepolymer, resulting in a polymer. The polymers physical properties vary with the degree of cross-linkage. This degree can be varied by the amount and type of curing agent added. In genera1, it is desired to cure the prepolymers to a degree such that the resulting polymer has the physical properties of an elastomer. Examples of prior art curing agents are toluene diisocyanate, isophorone diisocyanate, 3-nitraza-1,5-pentane diisocyanate and N100, a polyfunctional isocyanate produced commercially by Mobay Chemical Company.
It is usually desired to suspend other compounds in the polymer binder composition. For instance, a solid rocket propellant composition could comprise such a polymer having particulate fuel and oxidizer suspended in it. Examples of suitable fuel would be light metals and light metal hydrides. Examples of suitable oxidizers would be perchlorates and nitrates.